Endogenous α‐calcitonin gene‐related peptide mitigates liver fibrosis in chronic hepatitis induced by repeated administration of concanavalin A

Abstract Background: α‐Calcitonin gene‐related peptide (αCGRP) is a 37‐amino acid pleiotropic peptide that we previously showed to exert a hepatoprotective effect during concanavalin A (Con A)‐induced acute hepatitis. In the present study, we used αCGRP −/− mice to further investigate the antifibrogenic and hepatoprotective effects of endogenous αCGRP in Con A‐induced chronic hepatitis. Methods: Chronic hepatitis was induced in αCGRP −/− and wild‐type mice by repeated administration of Con A. Serum transaminases were measured to assess hepatic injury. The severity of fibrosis and the activation of hepatic stellate cells (HSCs) were analysed by Masson trichrome staining and immunohistochemical staining of α‐smooth muscle actin (α‐SMA) respectively. Altered expression of fibrosis‐ and inflammation‐related genes was evaluated using a quantitative real‐time polymerase chain reaction. Activation and proliferation of HSCs were analysed using both primary cultured HSCs from the mice and the LI90 HSC cell line. Results: αCGRP −/− mice showed more severe liver fibrosis than wild‐type mice in a Con A‐induced chronic hepatitis model. In histological and gene expression analyses, αCGRP −/− mice showed greater inflammatory and fibrotic changes, greater HSC activation and a higher incidence of apoptosis among nonparenchymal cells than wild‐type mice. Conclusions: Endogenous αCGRP mitigates liver fibrosis in chronic hepatitis induced by repeated administration of Con A. αCGRP could be a useful therapeutic target for the treatment of chronic hepatitis.